Having a service like PSA grade and authenticate them could be costly (see psacard.com), somewhere in the $100-$300 range per card. Establishing if they are authentic or reprints is really important, and probably the first thing you would want to do. Take them to a local card shop and ask the shop owner his/her opinion. I wouldn't sell them that way, though. Card shops usually only give around 25% value, which you can always beat. Depending on which cards they are, there can be good resources online to help you tell if they are authentic, reprints, or forgeries (tons of those floating around). As someone above mentioned, post a couple of decent pics in this thread and see if any of the collectors can offer some insights. Also, consider your source: where did you get them? If they were passed down through the family, that might suggest they are authentic. If you bought them at a garage sale or flea market, you might have to be more skeptical (though authentic cards do show up in those settings sometimes). Personally, I would not list them on ebay until I had a better understanding of what they really are--the card buying community here has pretty high standards and expectations for cards, especially vintage ones.
